Wax coating on printed paperboard



Oct. 30, 1962 c. T. DAVIS ETAL 3,

WAX COATING 0N PRINTED PAPERBOARD Filed May 28. 1959 INVENTORS CHARLES 7? DA V/S FRANCIS J. H/GG/MS ATTORNEY United States Patent Ofiice,

3,061,456 Patented Oct. 30, 1962 3,061,456 WAX COATING N PRINTED PAPERBOARD Charles T. Davis, Fayetteville, Ark., and Francis J. Higgins, Ponca City, Okla, assignors to Continental Oil Company, Ponca City, Okla, a corporation of Delaare Filed May 28, 1959, Ser. No. 816,574 20 Claims. (Cl. 117-45) This invention relates to wax compositions and more particularly to wax coating compositions having improved adhesion to printed paperboard.

As is well known in the art, paraffin Wax has been used to coat paperboard, and particularly paperboard milk cartons. It is also well known that, in the wax coating of milk cartons which have been printed with steamset inks, a great many waxes tend to blister or flake off the carton during storage. These blisters produce an unsightly appearance and, on those areas where the wax flakes off, the carton is not completely protected by the Wax film.

One method of alleviating this problem is by a careful blending of the wax composition. However, this method is beset by a number of disadvantages. Considerable experimentation is necessary to develop the proper blend. The selection of narrow fractions for use for this purpose may cause large quantities of waxes to be used only for cracking stock. Normally, the price of cracking stock is only 15 to 20 percent of that for refined wax. Obviously, a better method of solving this problem would be to find a material which will reduce or eliminate this blistering when used in small amounts.

In accordance with the present invention, we have found that the inclusion of a minor amount of a titanium organic compound in the wax causes the wax to have improved adhesion to printed paperboard. More specifically, we have found that the use of a titanium organic compound substantially reduces or eliminates blisters on printed paperboard when steamset inks are used.

Before proceeding to specific examples which illustrate our invention, it might be well to indicate in general the materials used therein.

As used herein and in the appended claims, the term wax includes paraffin wax as that term is commonly understood, and in addition the paraflin wax may contain such materials as higher boiling distillate waxes, microcrystalline wax, polyethylenes, and perhaps other additives. In general, the term paraffin wax is used to define the hard, crystalline wax commonly obtained from petroleum distillates, derived from mineral oils of the mixed-base or paraflin-base type. By the present refining methods, crude petroleum oil is subjected to distillation whereby it is separated into a series of fractions known as parafiin distillates. The wax is separated from the parafiin distillate by chilling and filtering or by the use of a solvent, as for example, propane or a ketone such as methyl ethyl ketone. The wax obtained by either of these two methods contains from to 50 percent oil and is generally referred to as slack wax. This slack wax is subjected to a sweating operation to remove the oil. The resulting wax usually contains 3 to 6 percent oil, but by proper sweating the oil content may be reduced to less than 1 percent. Also, the oil content may be reduced to an acceptable value by other methods such as solvent deoiling or press de-oiling. The final product is known as refined wax or paraffin wax and is graded according to the tensile strength, melting point, oil content, hardness, etc.

The preferred parafiin waxes for use in this invention have melting points in the range of 122-135" F.

Steamset inks and their application are well known in the art. In general, these inks comprise a glycol, a pigment, and a resin. It is our hypothesis that the resin and glycol prevent the wax from adhering properly to the printed paperboard. :It is to be understood that this is only a hypothesis, and we do not intend to be limited thereby.

The titanium compounds suitable for use in our invention have the formula:

0R1 RO.liORz 5R: where R, R R and R are either alkyl or acyl groups containing from 1 to 20 carbon atoms. Particularly suitable compounds are those of the above formula containing one acyl group of 12 to 20 carbon atoms and 3 alkyl groups of 3 to 5 carbon atoms. Examples of preferred compounds include the following:

Tributoxytitaniurn stearate Triisopropoxytitanium stearate Tributoxytitanium laurate Tributoxytitanium myristate Tetraisopropyl titanate Tetrastearyl titanate Tetrabutyl titanate Tetra-Z-ethylhexyl titanate A suitable range for the amount of titanium compound used is from 0.01 to 0.20 'weight percent, based on the wax. Preferably, we use from 0.03 to 0.10 weight per cent of the compound. Since we have found 0.20 percent to be completely effective in eliminating blisters, it is, of course, uneconomical to use larger amounts.

In order to disclose more clearly the nature of the present invention and the advantages thereof, reference will hereinafter be made to certain specific embodiments which illustrate the flexibility of the herein-described process. It should be clearly understood, however, that this is done solely by way of example and is not to be construed as a limitation upon the spirit and scope of the appended claims.

EXAMPLE I Tributoxytitaniuni stearate was prepared as follows:

Five grams of titanium butylate and 4.2 grams of stearic acid were added to a small beaker. The mixture was heated, with stirring, slowly over a flame until the odor of butanol could not be detected. The product was then cooled to room temperature.

EXAMPLE 11 Using the procedure of Example -I and making allowance for the difference in equivalent weight of lauric acid, tributoxytitanium laurate was prepared.

EXAMPLE III The laboratory procedure for determination of blistering is as follows:

The milk carton is dipped in the molten wax at about F. for about ten seconds, and then allowed to drain for about ten seconds, after which the wax is cooled by a. stream of air from a fan. Upon solidification of the wax, the carton is soaked for twenty-four hours in a one percent lactic acid-methylene blue solution at 40 F. The carton is then dried in air at room temperature, after which it is observed for blisters. A subjective estimate is made of the percentage of blistered area.

In this example a wax was used having the following characteristics:

Melting point, 128.0

Tensile strength, p.s.i 308 Viscosity at 175 F., cs 5.13 Percent oil 0.53

Various amounts of tributoxytitanium stearate were added to this wax. This was accomplished simply by melting the wax and stirring in the calculated amount. The waxes thus prepared, together with a control sample, were subjected to the procedure outlined previously. The results are shown in Table I.

Table 1 RESULTS OF BLISTERING TESTS ON WAX CONTAIN- ING TRIBUTOXYTITANIUM STEARATE Weight percent titanium Percent of total product in wax: areas blistered app.)

EXAMPLE IV In this example, a wax was used having the following characteristics:

Melting point, F 125.9

Tensile strength, p.s.i 360 Viscosity at 175 F., cs 5.09 Percent oil 0.41

To samples of this wax were added 0.1 percent (weight) of tributoxytitanium stearate and tributoxytitanium laurate. The wax blends thus prepared were subjected to the blistering test procedure given in Example III. The results are shown in Table II.

Table II RESULTS OF BLISTERING TESTS WAXES 0F EXAMPLE III Percent of total area Titanium product: blistered (app.)

Tributoxytitanium stearate 0 Tributoxytitanium laurate 1 EXAMPLE V In this example, a wax was used having the following characteristics Melting point, F 126.5

Tensile strength, p.s.i 275 Viscosity at 175 F., cs 4.66 Percent oil--- 0.40

This wax was subjected to the blistering test procedure given in Example III. The results are shown in FIGURE 1, which is a drawing of one panel of the milk carton. The blistered areas are shown in black.

EXAMPLE VI FIGURE 2Triisopropoxytitanium stearate FIGURE 3-Tetrabutyl titanate EXAMPLE VII Using the waxes of Examples III and IV, varying amounts of additional titanium compounds were added thereto. The wax blends thus prepared were subjected to the blistering test outlined in Example III. In all instances, it was found that the use of 0.2 percent (weight) or less of the titanium compound reduced the blistering to 1 percent or less. The compounds tested in this example were:

Tributoxytitanium myristate Tetraisopropyl titanate Tetrastearyl titanate Tetra-Z-ethylhexyl titanate From the results shown in the tables, the figures, and Example VII, it is evident that the use of 0.2 percent by weight or less of the titanium compounds described herein effects an elimination or very substantial reduction in blistering. It is to be understood that this improvement exists only when steamset inks are used for printing the paperboard.

The use of other additives in conjunction with the wax composition of our invention is permissible, and in many cases may be desirable.

While particular embodiments of the invention have been described, it will be understood, of course, that the invention is not limited thereto, since many modifications may be made; and it is, therefore, contemplated to cover by the appended claims any such modifications as fall Within the true spirit and scope of the invention.

The invention having thus been described, what is claimed and desired to be secured by Letters Patent is:

1. In a process in which printed paperboard, which has been printed with steamset inks, is coated with paratlin wax and in which blisters are formed in the coating, the improvement comprising substantially eliminating the formation of said blisters by coating the printed paperboard with a parafiin wax containing from about 0.01 to about 0.20 percent by weight of a titanium compound having the formula:

wherein R, R R and R are selected from the class consisting of alkyl and hydrocarbon acyl substituent groups containing from 1 to 20 carbon atoms.

2. The process as defined in claim 1 wherein the titanium compound is tetraisopropyl titanate.

3. The process as defined in claim 1 wherein the titanium compound is tetrastearyl titanate.

4. The process as defined in claim 1 wherein the titanium compound is tetrabutyl titanate.

5. The process as defined in claim 1 wherein the titanium compound is tetra-Z-ethylhexyl titanate.

6. The process as defined in claim 1 wherein the titanium compound has the formula where R, R and R are alkyl groups containing from 3 to 5 carbon atoms and R is a hydrocarbon acyl group containing from 12 to 20 carbon atoms.

7. The process as defined in claim 6 wherein the titanium compound is tributoxytitanium stearate.

8. The process as defined in claim 6 wherein the titanium compound is triisopropoxytitanium stearate.

9. The process as defined in claim 6 wherein the titanium compound is tributoxytitanium laurate.

10. The process as defined in claim 6 wherein the titanium compound is tributoxytitanium myristate.

11. As an article of manufacture printed paperboard, said printed paperboard having been printed with steamset inks and having a coating of paraflin wax, said parafiin wax containing from about 0.01 to about 0.20 weight percent of a titanium compound having the formula where R, R R and R are selected from the class consisting of alkyl and hydrocarbon acyl substituent groups containing from 1 to 20 carbon atoms.

12. An article of manufacture as defined in claim 11 wherein the titanium compound is tetraisopropyl titanate. 13. An article of manufacture as defined in claim 11 wherein the titanium compound is tetrastearyl titanate.

14. An article of manufacture as defined in claim 11 wherein the titanium compound is tetrabutyl titanate.

15. An article of manufacture as defined in claim 11 wherein the titanium compound is tetra-Z-ethylhexyl titanate.

16. An article of manufacture as defined in claim 11 wherein the titanium compound has the formula Ra where R, R and R are alkyl groups containing from 3 to 5 carbon atoms and R is a hydrocarbon acyl group containing from 12 to 20 carbon atoms.

17. An article of manufacture as defined in claim 16 wherein the titanium compound is tributoxytitanium stearate.

18. An article of manufacture as defined in claim 16 wherein the titanium compound is triisopropoxytitanium stearate.

19. An article of manufacture as defined in claim 16 wherein the titanium compound is tributoxytitanium laurate.

20. An article of manufacture as defined in claim 16 wherein the titanium compound is tributoxytitanium myristate.

References Cited in the file of this patent UNITED STATES PATENTS 2,621,193 Langkammerer Dec. 9, 1952 2,643,262 Bostwick June 23, 1953 2,955,958 Brown Oct. 11, 1960 

1. IN A PROCESS IN WHICH PRINTED PAPERBOARD, WHICH HAS BEEN PRINTED WITH STAEMSET INKS, IS COATED WITH PARAFFIN WAX AND IN WHICH BLISTERS ARE FORMED IN THE COATING, THE IMPROVEMENT COMPRISING SUBSTANTIALLY ELIMINATING THE FORMATION OF SAID BLISTERS BY COATED THE PRINTED PAPERBOARD WITH A PARAFFIN WAX CONTAINING FROM ABOUT 0.01 TO ABOUT 0.20 PERCENT BY WEIGHT OF A TITAIUM COMPOUND HAVING THE FORMULA: 